全球环境变化与人体健康

以全球增暖为标志的全球环境变化已经出现。这一变化对人体健康和人类社会的生存和未来发展将产生极为重大的影响。人类自身活动是引起全球环境变化的一个最为活跃的因子。但是,对人类活动,包括个人和社会集体行为,对全球环境变化的影响和机制,全球环境变化又是怎样反作用于人类社会,以及人类如何适应未来全球环境变化等问题研究甚少。由于人体健康直接关系到每个人,“环境变化与人体健康问题”应该作为全球环境变化研究中的研究核心之一,应加强社会科学界、环境科学界和医学界之间的合作研究。同时,应积极开展国际合作,加大研究成果的宣传力度,增强全民环保意识。       

Patterns in groundwater chemistry resulting from groundwater flow

 Groundwater flow influences hydrochemical patterns because flow reduces mixing by diffusion, carries the chemical imprints of biological and anthropogenic changes in the recharge area, and leaches the aquifer system. Global patterns are mainly dictated by differences in the flux of meteoric water passing through the subsoil. Within individual hydrosomes (water bodies with a specific origin), the following prograde evolution lines (facies sequence) normally develop in the direction of groundwater flow: from strong to no fluctuations in water quality, from polluted to unpolluted, from acidic to basic, from oxic to anoxic–methanogenic, from no to significant base exchange, and from fresh to brackish. This is demonstrated for fresh coastal-dune groundwater in the Netherlands. In this hydrosome, the leaching of calcium carbonate as much as 15 m and of adsorbed marine cations (Na⁺, K⁺, and Mg²⁺) as much as 2500 m in the flow direction is shown to correspond with about 5000 yr of flushing since the beach barrier with dunes developed. Recharge focus areas in the dunes are evidenced by groundwater displaying a lower prograde quality evolution than the surrounding dune groundwater. Artificially recharged Rhine River water in the dunes provides distinct hydrochemical patterns, which display groundwater flow, mixing, and groundwater ages. Received, May 1998 · Revised, August 1998 · Accepted, October 1998     

Sulfate transport in a Coastal Plain confining unit, New Jersey, USA

 A transient 1-D, two-pathway non-equilibrium deterministic advective dispersion model was used to examine the distribution of chloride (43–100 mg/L) and sulfate (57–894 mg/L) concentrations in the 35-m-thick section of the Lower confining unit, Atlantic Coastal Plain, New Jersey, USA. The model was used to constrain hypotheses about how pore-water chemistry changed over time. Explanations of the solute concentrations were explored by inverse and direct methods given a few known constraints, including concentrations of pore-water constituents from 12 core samples, reported simulated flow rates, and estimated hydrogeologic properties. The hypothesis that is best supported by the model results is that the distribution of chloride and sulfate concentrations in the confining unit reflect the history of the aquifer system since it was filled with seawater at the last eustatic high, about 84×10³yr BP. The model simulates fresh-water flushing of the seawater-permeated silts at a steady upward pore-water flow velocity of 8.8×10^–6 m/d, with a dispersion coefficient of 9.2×10^–7 m²/d, a dimensionless partition expression for chloride, β_Cl=0.981, and a dimensionless exchange coefficient, ω_Cl=0.31×10^–2. Sulfate concentrations were simulated over the flow path using flow and dispersion values calculated for chloride transport plus a retardation term. Parameters for sulfate transport include retardation coefficient=4.51, β_SO4=0.994, and ω_SO4=0.31×10^–2. Sensitivity analysis indicates that the model is most sensitive to flow velocity, and that fresh-water flushing of the confining unit is best simulated by having seawater concentration levels at the inflow boundary of the confining unit exponentially decrease with a concentration half-life rate of 825 yr. Received, January 1997 / Revised, April 1998, October 1998, January 1999 / Accepted, January 1999     

An Overview Of The Origin Of Life: The Case For Biological Prospecting On Mars

Studies of the Earth's earliest biosphere have suggested a close coupling between the evolution of early life forms and the physical and chemical evolution of the planetary surface. From a biological perspective there were many similarities between early Earth and early Mars. This has led to the idea that an origin of life event may have occurred on Mars, leading to the development of microbial life. Various theories have been advanced to explain the origin of life on Earth, and these are reviewed with relevance to Mars. If traces of past or present biogenic activity are to be found on Mars, then the most likely place to prospect is several kilometers below the surface where liquid water might be stable. Such prospecting may best lend itself to human exploration. This revised version was published online in July 2006 with corrections to the Cover Date.     

洱海地区一万多年以来气候环境演化的湖泊沉积记录

根据对洱海北部10．8m深水区ES孔沉积物高分辨率的孢粉、粒度、碳屑、藻类分析,结合AMS^14C测年数据,划分了11个阶段,恢复了一万多年以来云南洱海地区气候环境演化序列．全球性的降温事件在该地区都有明显的反映,包括9900aBP(Younger Dryas)、8500aBP、7100aBP、5100aBP左右的四次冷事件,6800—5500aBP为全新世水热配置最佳期,距今2400年开始该地区出现较为明显的人类活动．     

长江输出溶解态无机磷的通量模型灵敏度分析及情景预测

研究河流向河口及沿海海域输送的物质通量是一项国际性前沿课题.基于人类活动影响流域营养盐输移的定量分析,应用Global NEWS模型模拟1970-2003年长江输出溶解态无机磷(DIP)的通景,对其不同来源的贡献率进行了分析,并基于千年生态系统评估对未来社会经济发展规划的情景,对2050年长江输出DIP的通量进行预测....     

洪湖人类活动的沉积物记录

对洪湖150cm长的沉积物样芯进行了TOC、TN、TP、Ca、硫化物测试和AMS定年,在此基础上对洪湖地区人类活动的湖泊沉积响应进行了讨论.TOC和TN的含量呈现相似的变化规律,它们在样芯顶部和底部都出现显著峰值,而中部变化平坦,表示1500年来洪湖环境变演的三个显著不同的阶段;TP从过去到现在总体呈上升的趋势,但上升的幅度不大,这与磷在沉积物中复杂的循环机制有关;Ca的剖面变化显示为底部含量高上部低,其变化情况较复杂;硫化物在顶部15cm的含量比背景值略高,可能指示了上个世纪人类对铁矿和矿物燃料开采强度的增大.     

从自然变化过程中分离人类活动的探讨--以山东利津剖面为例

根据一天然剖面的炭屑、孢粉、年代学分析结果,研究了2500a以来的气候变化过程.在详细历史资料基础上,通过对比发现的炭屑异常峰值与历史上几次人口增殖和火灾有关,某些孢粉种属的变化则可能是人类耕种的结果.这说明只要提高研究的分辨率,对于人类活动事件是可以把它从自然变化过程中分离出来的,这对改造环境、恢复生态是非常重要的.     

流域人类活动与降水变化对黄河三角洲造陆过程的影响

利用海图和遥感影像资料,确定了不同时期黄河三角洲的造陆速率,并将造陆速率的变化与流域降水和人类活动的变化相联系.研究发现,三角洲造陆速率与年降水量之间具有正相关关系,与各项水土保持面积和人类引水量之间具有负相关关系.运用多元回归分析方法,建立了黄河三角洲造陆速率与年降水量、梯田林草面积、淤地坝造地面积、人类年引水量等因子之间的多元回归方程.该方程表明,年降水量越大,三角洲造陆速率越大;梯田、林草面积和淤地坝造地面积越大,三角洲造陆速率越小;人类净引水量越大,三角洲造陆速率越小.     

以土壤水分为参变量的根冠系统模拟调控模型

针对以往在建造各类作物生长模拟模型中,对构成作物整体功能的根、冠关系这一系统未予(充分)考虑的现状,在整体、器官水平上,探讨、分析了根、冠之间相互关系,归纳了根、冠系统各种特性,并构建了以土壤水分作为调控因子的根、冠互相藕合机制模型。模型辨识及两年冬小麦试验数据验证结果表明,该模型具有较强普适性和较高模拟预测精度,不仅能模拟预测出不同土壤水分条件下根、冠干物重,研究根、冠间互利互制消长反馈关系,而且还可根据不同生产目标规划灌溉方案。